Naturally Abundant 17O Nuclear Magnetic Resonance and the Determination of Oxygen Functionalities in Synthetic Fuels

We report the successful use of nuclear magnetic resonance (NMR) of naturally abundant 17O to determine oxygen functionalities in synthetic fuels. Heteroatomic (N, S, O) species are a significant factor in the processability, stability, and value of natural and synthetic fossil fuels. Sulfur and nitrogen removal has received much attention, but oxygen is also quite significant, since it is the most abundant heteroatom in most coals and for its removal, hydrogen must be consumed. This can impact adversely the economics of coal liquefaction. Oxygen bonds (e.g., ethers) on the other hand may be the “weak link” in the depolymerization of coal. Also, oxygen functionalities affect the stability of fuels, and during desulfurization and denitrogenation, the same oxygen functionalities compete and may interfere with these reactions in a fuel upgrading process. Thus, there is need for the unequivocal identification and quantitative determination of oxygen functionalities, for their understanding could aid materially in the design of processes to produce and upgrade synthetic fuels in a cost-effective manner. (1,2)